The Stovebolt Site Forums The Shop Area Engine Shop carb freezin-heat riser fixed, what now

Ok, my 53 w/216 is still freezin up on the bottom of the carb where she bolts to the intake. After some help (thanks wrenchbender) the heat riser got a new 'used' spring, Ive got a new one comin but was to impatient to wait!

She isnt freezin up as bad but almost takes 15-20 minutes of idling before she even starts to thaw the frost a little, better then without the heat riser working though.

Any ideas? Thanks, Jeff

For an experiment, why not try jamming the heat riser in the heat position? I can't remember what the passage way looked like for the exhaust but mabe it is possible for it ti be restricted by carbon.

I thought thats what the spring did? Held it up to heat the intake up until she was all warmed up and the spring loosens and the riser falls down?

What carb are you using & is there a spacer under it? What climate conditions does this happen?

Okay, Carter yf (original carb), It looks like theres a 1/2" spacer between. Also looks like its gonna be a pain to take off if need be-years of dirt and grime.

It happens at anytime. Its 45 here now, have tried it in mornin, noon, night, etc...

This is drivin me crazy! Thanks

You might take the spacer out. you will have to adjust or modify the linkage. If the carb. was replaced at one time it could be to small for the engine. Where is Carbking I,m running out of ideas.

try addding a bottle of Heet,I have been told(by mechanic/service station owner) there is no alcohol added to fuel(no diff in winter/summer fuel)nowdays due to everything being injected. I have never had a problem until the past couple years. I had my 79 f350 die one cool humid morning, popped the hood-carb was frozen over on the sides. When engine heat melted it truck fired back up & hasn't done it since(I add Heet). I first noticed it when my truck would die at the same stop sign each cool damp morning but not when it was dry or warmer. brian

Jeff - it has to do w/ the dew point - certain humidity at certain temps - I fixed a 250 I had that insisted on carb icing under conditions that didn't affect other's in the fleet - scrounged a heat shroud from an exhaust manifold at the wreckers and put a tube from it to the air cleaner - the slight warming of the intake air cured it immediately

a way to deal w/ it is to start the engine, idle for 2 minutes, shut it off, wait 2-3 minutes and start it again, will usually have spread enuff heat to be ok

Bill

Thanks for the help. Ill give it a try next Bill.
I actually just through some heet in her just in case there was water in the tank, no help.

I have a goofy question now, I thought at first the carb was sucking air through a pinhole(bad gasket etc...) and that was making the problem worse. Cant find any though...

So theoretically, the main throttle linkage goes through the last piece of the carb where she bolts to the intake(also where frost occurs), and the carb rebuild instructions show no o-rings on that linkage, if I added them (making it airtight)would it make a difference? Meaning less surface space for cold air coming into the carb would mean less moisture condensing on different areas of the carb also. Makes sense right?

Also, do they make an aluminum piece for these, aluminum would condense less moisture then steel which is what is on there now.

darn I wish I had a digital camera and could post a few pics of how bad shes frostin up! Guess that just moved up on the priority list!

Thanks again for all the help, Jeff

I just know its gonna be somethin so stupid when I find it to!

Red58 is right on the money. One other possibility: is the vehicle blowing black smoke after it warms up?

Carburetor icing is a result of the "heat of vaporization" of changing gasoline from the liquid state to the gasous state. This is an endotheric change (it requires heat). The required heat is removed from the air thus cooling the air (and creating frost deposits). If the carburetor is too rich, it requires more heat to vaporize the fuel, and contributes to the icing problem.

Other than the solution suggested by red58, another possible solution is to install a air deflector in front of the carburetor to keep air from the fan being blown on the carb. Lots of imports in the early 1970's had an air cleaner with switch that allowed pulling either fresh air or heated air into the engine.

Jon.

No smoke at all. Now that the carbs rebuilt its not running as rich either. Still using the oil bath air filter to, assuming a paper filter would allow it to suck more cold air freely?

hey thanx Jon! I got one right!

you might actually try a paper filter, or none at all, a time or 2 and see if there's a difference - the convoluted route the air takes thru the oil bath filter is prolly speeding up the velocity as well as maybe upping the humidity which would cool the air

Bill

I know you've all seen the tin shields on the exhaust manifolds of the 60's & 70's. The idea there was to direct warm air to the carb inlet, or snorkel tube on some of the air filters. In the 70's type Chevy v-8's there was a butterfly flap in the snorkel, that was actuated by vacuum. The warmer the engine got the more vacuum, and the butterfly opened. Ya might also check the forum and look at the post that bigmacdaddy wrote, He's got pictures too. Hope this is helpful
resto44